Method and apparatus for handling strands



Feb. 4,- 1941. j P M COLE 2,230,347

METHOD AND APPARATUS FOR HANDLING STRANDS Filed Nov. 25, 1939 INVENTOR By P. COLE A TTORNEV Patented Feb. 4, 1941 "U N lT-ED STATES iPATiENT OFF-ICE -METHOD AND APPARATUS 'FOR HANDLING STRANDS Application November 25, 1939, Serial No. 306,117

8 Claims.

This invention relates to a method and an apparatus for handling strands, and more particu larly to a method of and apparatus for handling strands of elastically extensible material and to impose upon such strands a constant and controllable linear tension.

Of recent years there have been many and various developments in industry of apparatus and procedures in which elastically extensible strands, e. g. of rubber, latex, chloroprene, and the like are treated or handled alone or combined with like strands or with inextensible strands of various kinds while in a state of sufficient linear tension to be longitudinally stretched or extended. It has been found in dealing with such strands that it is a difficult problemto impose a linear tension upon them which shall be constant at a predetermined and adjustably variable value. Especially is it found that in the case of some tensioning devices taken from the older art dealing with inextensible strands or with inelastically and permanently extensible strands, which devices depend for their tensioning effect upon a friction brake, the tension tends to accumulate in the strand by elastic deformation up to a certain value, whereupon the resistance to progress is overcome and the stretched portion of the strand leaps forward, pulling an unstretched portion after it before the resistance to progress again becomes effective.

An object of the present invention is to provide a strand tensioning method and device, particularly applicable to an elastically extensible strand, although not limited to such, which shall be simple in operation and sturdy instructure, conveniently adjustable as to effect, and simple, reliable and effective.

One embodiment of the invention in a device to practise the method may comprise a rod. coaxially housed within a tube with corresponding diametrically axially located slots in both through which a strand to be tensioned passes in combination with means to vary the orientation of one slot relatively to the other responsively to variations in the tension of the strand.

Other objects and features of the invention will appear from the following detailed description of an embodiment thereof in an apparatus for supplying elastically extensible strands of rubber to a knitting machine, braider or other analogous machine, taken in connection with the accompanying drawing in which the same reference numerals are applied to identical .parts in the several figures and in which Fig. l is a broken view in front elevation of an-apparatus constructed in accordance with the invention;

Fig. 2 is an enlarged broken view on the line 2-2 of'Fig- 1;

Fig. 3 is a broken plan view of the showing of L Fig. 2; and

Fig.4 is an enlarged section on the line=:-4-4 of'Fig. 3.

In theapparatus herein disclosed a plurality of strands 19 of rubber or other elastically'extensible material wound on stationary supply spools 20 is to be braided, under tension sufficient to stretch the strands, about a core strand drawn from some suitable supply means not shown, by-means of a suitable braiding apparatus not shown but to be thought of as mounted on the framework shown in Fig. 1 above the broken upper edge-thereof. A strand tensioning device embodying the specific invention is provided for each of the elastic strands l9 and this plurality of devices may conveniently be mounted on a crossbar 2| of the machine frame. As all of the tensioning devices are identically similar to each other, a description of one will be sufficient, and the one at the extreme left of Fig. l is selected for this purpose.

A cylindrical rod 22 is supported horizontally in suitable pedestals-'23, .23 and is held against rotation by any suitable means such as pins .24. The rod 22 is formed with a longitudinal, central, vertical slot 25 of a width to pass the strand i9 freely. A sleeve 26 is snugly but freely rotatablymounted on the rod and is formed with a longitudinal, central, vertical slot 21, ofabout the same width as the slot 25 and normally in substantial alignment therewith. A vertical arm or lever .28 is rigid on or integral with the sleeve 26 and has a freely rotatable control sheave 29 mounted on its outer end. The lever 28 is urged continually toward the right (Fig. 2) We spring 38 secured. at one end to the lever and at the other end to any suitable spring tension adjusting meanssuch as the screw threaded rod13land adjusting nut 32. An adjustable stop member 33 prevents the lever from being drawn too far from its normal position should the strand run out of breakandthus facilitates threadingup the apparatus.

A' strand l9, drawn upwardlybymeans not shown, :comes off over the upper head of. aistationary, or other, supply spool andpasse'syiup through a suitable'aperture 34, if necessary,.,in the machine frame and through the aligned .slots 25and 21. Thence it passes-overthe freely rotatable. control sheave .29,and over. a freely rotatable guide shaft common to all of the strands I9. The shaft 35 may be an idler, as shown, driven by the strands passing over it, or it may be driven by any suitable means to have the same peripheral speed as the linear speed of the strands.

The spring 30 tends to draw the lever 28 and therewith the sheave 29 to the right and the tension of the strand, which is being pulled upwardly by the machine above, tends to draw the sheave and therewith the lever to the left. The spring 30 is so adjusted that the action of the rod 22 and sleeve 26, as described below, will hinder the progress of the strand sufficiently to impose the desired predetermined tension thereon. The spring is adjusted to rotate the slot 21 more or less out of alignment with the slot 25 so that the strand passing through the slots is more or less pinched at both the upper and lower ends of the slot 25 by the partial closing of the ends of the slot by the edges of the sleeve 26.

It has been found when the attempt is made to use for elastically extensible strands tensioning devices developed in the prior art for imposing tension on wires, textile cords and threads, and other inextensible cords, that such devices frequently fail to operate satisfactorily with strands of rubber and the like. It appears that the tension and the consequent stretching of an extensible strand will accumulate, just beyond the point where the tension is being created,up to a certain critical value, when the surface hold of the device on the strand is abruptly broken and the strand leaps forward with rapidly falling tension until the device is able to take hold again. Hence through such devices, a strand of this character will pass only in successive jerks and with large and violent variations in tension.

In the device herein disclosed it will be clear that the detaining grip of the slotted rod and slotted sleeve on the strand is double, being effected simultaneously at both ends of the slot 25. The result is that tension in the portion of the strand above the outlet of the slot 25 (Fig. 4) is only partially transmitted backward past the outlet of the slot to the portion of strand momentarily within the slot 25, and is not transmitted at all, ordinarily, past the lower grip of the device on the strand at the inlet of the slot 25 and to the loose strand below. Now when the tension above the outlet of the slot becomes sufficiently great to break the outlet grip on the strand, the portion gripped at the outlet jumps forward and the tension is transferred momentarily back to the inlet grip. In so doing, however, the tension is diminished in stretching the only partly stretched portion of strand between the two grips; and, instead of an unpredictably large length of strand suddenly slipping forward, only so much moves as corresponds to the stretching of the portion between the two grips. While this is happening, the tension is momentarily diminished as just noted, the spring draws the control sheave to the right and the effectiveness of both grips is increased and the outlet grip takes hold again before the inlet grip can be also overcome.

The strand does not in theory progress with uniform motion and speed and under uniform tension through the device disclosed. It progresses by jumps whose magnitude depends primarily upon the length of the slot 25. In practise it is found that when the dimensions of the rod 22 and sleeve 26 and of the slots 25 and 2'! are suitably proportioned to the size and stretchability of the strand to be handled and to the tension necessary to produce the desired degree of stretching of the strand, the vibratory variation in tension becomes practically negligible in the strand as delivered from the control sheave 29.

In using the words grip, gripping, retard, retarding and the like in the above description and in the appended claims, it is not generally intended to be thought that the portions of strand constricted at any given moment between opposing and approximated edges of the ends of the slot 25 and of either part of the twin slot 21, are prevented from motion, although in extreme instances this may happen. It is rather the case that the elastically laterally compressible as well as longitudinally extensible strand moves substantially continually through the narrowed opening, the resistance to its motion being presumably due to the constricting effect as well as to any friction.

The embodiments of the invention herein disclosed and described are illustrative and may be varied and departed from without departing from the spirit and scope of the invention as pointed out in and limited solely by the appended claims.

What is claimed is:

1. An apparatus for tensioning an elastically extensible and longitudinally advancing strand which comprises frictionally engaging means to pinch more or less severely a strand at one point thereof, means to pinch more or less severely the strand at another point thereof, and means responsive to variations in the tension of the strand to vary the pinching effect of the two strand pinching means.

2. An apparatus for tensioning an elastically extensible and longitudinally advancing strand which comprises a stationary member, a movable member cooperating therewith to retard a strand at two distinct points of the strand, and means responsive to variations in the tension of the strand to move the movable member to vary the retarding effect of the two members upon the strand.

3. An apparatus for tensioning an elastically extensible and longitudinally advancing strand which comprises a stationary member, a movable member cooperating therewith to grip a strand at two distinct points of the strand, and means responsive to variations in the tension of the strand to move the movable member to vary the gripping effect of the two members upon the strand.

4. An apparatus for tensioning an elastically extensible and longitudinally advancing strand which comprises a stationary member, a movable member cooperating therewith to pinch a strand at two distinct points of the strand, and means responsive to variations in the tension of the strand to move the movable member to vary the pinching effect of the two members upon the strand.

5. An apparatus for tensioning an elastically extensible and longitudinally advancing strand which comprises a stationary member, a pivotable member cooperating therewith to grip a strand at two distinct points of the strand, and means responsive to variations in the tension of the strand to turn the pivotable member to vary the gripping eifect of the two members upon the strand.

6. An apparatus for tensioning an elastically extensible and longitudinally advancing strand which comprises a cylindrical member formed with a longitudinal slot therethrough, a sleeve member rotatable thereon and formed with two longitudinal slots alignable simultaneously with the slot in the cylindrical member to form a continuous passageway through both for the passage of a strand, and means responsive to variations in the tension of the strand to rotate one of the two members relatively to the other and thereby constrict the strand simultaneously to a varying degree at both ends of the slot in the cylindrical member.

'7. An apparatus for tensioning an elastically extensible and longitudinally advancing strand which comprises a cylindrical member formed with an aperture therethrough, a sleeve member rotatable thereon and formed with two apertures alignable simultaneously with the slot in the cylindrical member to form a continuous passageway through both for the passage of a strand, a

lever secured to one of the two members to rotate the same relatively to the other member, a control sheave on the lever to receive and support the strand emerging from the passageway whereby the tensioned strand tends to move the lever in one direction to constrict the strand simultaneously to a varying degree at two distinct points thereof in the passageway, and spring means tending to turn the lever in the other direction.

8. The method of tensioning an elastically extensible and longitudinally advancing strand which comprises the steps of pinching a strand between frictionally engaging members simultaneously at two distinct points thereof and var y-, ing the intensity of the pinching effect simultaneously at both points in accordance with variatiorrs in the tension of the strand.

PAUL M. COLE. 

